This invention relates to a method and apparatus for producing chip or swatch bearing sheets having an array of colored chips or swatches as on a color chart.
Currently, a commercial process to form such color sheets much as shown in U.S. Pat. No. 4,061,521 provides a high speed operation (e.g., 3,000 to 6,000 charts per hour) in which base sheets are fed continuously through an adhesive applying station and then through several swatch-forming and transferring stations, where color swatches are severed from reels of continuous webs or ribbons as the ribbons travel past the severing means. The severed swatches are then transferred to and deposited upon the adhesive locations on the base sheet. The trend in the color chart industry has moved toward using larger color charts (e.g., 25 to 28 inches long and 8 to 10 inches wide) as well as larger color chips. The use of larger chips corresponds to larger charts if the charls are to bear the same number of chips as before on the smaller charts. Due to a number of factors including the current cutting blade size, larger color charts must be fed through the current apparatus on the chart's long axis. When adhesive is applied to base sheets having a substantial differential in printing across the sheet surface and these sheets are fed into the current apparatus on their long axis, the base sheets often bow or buckle, causing machine jams or producing defective charts.
Another problem created by feeding charts through the apparatus on their long axis is that it necessitates longer, multi-station set-ups, some reaching over 70 feet in length for the larger color charts. These longer multi-station set-ups require more floor space, more maintenance, and more personnel to operate. Additionally, when there are not enough individual stations or available floor space, the larger color charts must be manufactured in a two-pass process, creating obvious manufacturing inefficiencies. In a two-pass process, larger charts are fed through the apparatus twice, with some of the chart's swatch rows applied in the first pass and the remaining swatch rows applied when the same chart is fed through the apparatus a second time.
With the current apparatus, each row of color swatches is applied by a separate swatch-cutting and transferring station, with a number of stations equivalent to the number of color rows linked together to produce the color chart. For example, a typical larger color chart might have eighteen rows of color chips down its long axis but only seven rows down its short axis. Feeding this chart through on its long axis would require eighteen linked stations, while feeding it through on its short axis would require only seven stations.
Fewer stations equates to an increased production rate and reduced labor and process costs. Decreasing the base sheet travel time results in a much greater hourly production rate. The base sheet's travel time through seven rather than eighteen stations can be reduced to approximately one-third of the current travel time, using the same conveyor speeds in each instance. Additionally, the reduction from eighteen to seven stations substantially eliminates the cost of eleven stations. This cost reduction is offset somewhat by the fact that the seven short-axis stations are wider than the first seven stations of the eighteen station line. However, the same number or fewer people operating the current long-axis machine may be used to operate the higher production short-axis machine, thereby providing additional production without an increase in labor costs.
The shorter travel distance also lessens manufacturing spoilage, in that there is less opportunity for the base sheets to become misaligned or distorted in the shorter travel distance. Thus, there is a need for a commercial apparatus operating at high speeds of 3,000 to 6,000 cards per hour with base sheets traveling on their short axis, thereby eliminating the problems mentioned above while improving productivity.
Although feeding the color chart through on its short axis decreases the number of individual swatch-forming and transferring stations, it necessitates longer cutting blades to accommodate the larger loads of color reels. For example, while a short-axis feed of the larger color chart described earlier would require only seven stations, each station would now be loaded with up to eighteen reels of color ribbons, instead of only seven as with the current long-axis feed. Efforts to utilize longer cutting blades of the type disclosed in the aforementioned patent have not been successful in cutting swatches at the high speeds desired, however, due to the fact that the current severing means creates non-uniform swatches. Altering the taper or using a non-tapered blade were also unsuccessful, as it was found that the non-tapered blade could not cut cleanly through the larger loads of ribbon reels.
The current severing means is comprised of a rigidly attached, cylinder-mounted blade that cuts through multiple color ribbons aligned side-by-side as they are pulled between the rotating cylinder and a stationary anvil. As the ribbons travel between the cutting blades, the tapered blades begin to cut the ribbons at one end of the ribbon stack in a scissor-like motion, continuing to cut the remainder of the ribbons as the knife cylinder turns and the cutting blades close together along a point contact across the cylinder. The actual cutting path across the cylinder is not perpendicular but somewhat helical due to the continuous turning of the knife cylinder and the scissor-like cutting motion from the tapered blades. This cutting path creates swatches which are shaped somewhat like parallelograms, and/or are different in size from one end of the ribbon stack to the other. While the discrepancy in shape or size is minor for smaller ribbon loads, it becomes more pronounced with a short-axis feed, where the blade must cut across a longer cylinder through a larger load of ribbons. Attempts to remedy this problem by altering the cutting blade taper or by using a non-tapered cutting blade were also unsuccessful, evidenced by jagged or incomplete cuts across the cylinder. A non-tapered blade contacts the ribbons simultaneously across the cylinder along a line contact rather than a point contact as with a tapered blade. Contacting the stationary anvil along a line contact creates a greater amount of force, especially across a wider expanse of cylinder. This additional force likely caused the rigidly attached cutting blade to impact, catch on the fixed anvil, and then disengage from the anvil before the cut was complete, resulting in jagged or uncut portions of ribbon across the cylinder. Thus, there is a need for an apparatus which incorporates a severing means which is able to accommodate the larger ribbon loads that accompany a short-axis feed, thereby eliminating these problems while improving productivity.